Excessive stimulation or suppression of physiological systems early in development leads to long-term changes in the regulatory dynamics of these systems in later life. Addiction to opiate drugs during pregnancy or exposure to stressful environments that stimulate endogenous opiate release is responsible for a wide range of changes in the brain and behavior of the offspring. The endogenous opiate system is one of many factors controlling the functional integrity of the immune system. The long-term goals of this research project are to identify the relationships between early opiate environment and later immune function using a rodent model and to determine whether perturbations of the early opiate environment induce later immune dysfunction. The experiments in this proposal are specifically designed to determine if maternal exposure to morphine influences the offsprings' cellular immune responses. This will be achieved by measuring the proliferative responses of T-cells and B- cells to mitogens, by quantitating the immunoglobulins in the offspring, by measuring the type and number of lymphocytes in the spleen, and by investigating natural killer cell activity in offspring of opiate-treated versus control animals. Other experiments will test the potential role of brain opiate receptors in immune dysfunction. Knowledge of how opiate exposure during early development influences later immune function may help design optimal strategies for treating disease in individuals born to addicted mothers.